Fluid heat exchange apparatus



y 0, 1938. c. 5. SMITH 2,116,546

Q FLUID HEAT EXCHANGE APPARATUS Filed March 29, 1935 3 Sheets-Sheet 1 INVENTOR 7 ATTORNEY May 10, 1938. c. s. SMITH FLUID HEAT EXCHANGE APPARATUS Filed March 29, 1935 5 Sheets-Sheet 2 000 00 00000 00 00000 000 00000 000 oofl woo 00000 000 00000 000 00000 000 000 00 00000 00 m aw Ga a May 10, 1938. E Q s, sMn-H 2,116,546

FLUID HEAT EXCHANGE APPARATUS Filed March 29, 1935 3 Sheets-Sheet 5 Ill/11111014 INVENTOR Charles 5 Smii/z I AT ORNEY Patented May 10, 1938 UNITED STATES PATENT OFFICE FLUID HEAT EXCHANGE APPARATUS Application March 29, 1935, Serial No. 13,694

3 Claims.

This invention relates to fluid heat exchange apparatus, and it is exemplified herein as an embodiment of a water tube steam boiler with a superheater.

It is an object of the invention to provide for the regulation of superheat over a wide range of boiler capacity.

It is an inherent characteristic of some super heaters that they produce a variable superheat in response to changes in boiler ratings. This is particularly true of a superheater which is mainly heated by convection transmitted heat. This is an undesirable condition in modern steam power plants, and it is a further object of this invention to provide means for overcoming this defect.

Other objects of the invention will appear in the accompanying description of the superheater boiler shown in the drawings, in which:

Fig. l is a view in the nature of a vertical section through the steam boiler and superheater installation.

Fig. 2 is a view in the nature of a partial vertical section taken on the line 2-2 of Fig. 1.

Fig. 3 is an enlarged view in the nature of a vertical section of part of the structure indicated in Fig. 1.

Fig. 4 is a detailed vertical sectional view of a part of the control mechanism, taken on the line 4-4 of Fig. 3.

In the drawings, there is shown a superheater H) of the multiple loop type. It receives satu' rated steam through the supply conduits l2 and the inlet header I 4 from the steam and water drum l6 of the boiler and is contacted by the furnace gases after they have passed across the bank of horizontally inclined steam generating tubes l8.

The boiler shown in the drawings is substantially a single pass boiler, whereas the superheater may be said tohave a primary section and a secondarysection subject respectively to contact with the furnace gases in difierent gas passes. The superheater baffle 20 separates these gas passes.

At the left of the balile 20 shown in Fig. 1, the primary section of the superheater is subject to contact with the furnace gases leaving the water tube bank I8. After the gases have been progressively cooled by passing over the tubes of this section they normally pass downwardly at the rightof the baffle 20 and over the secondary section 22 of the superheater.

As boiler ratings increase it is the tendency of superheaters located as here shown to give increased superheat, but this may be prevented, and a constant superheat maintained, in the illustrative apparatus, by control of the flow of the gases passing over the secondary section of the superheater. The apparatus shown for elfecting this control will now be described.

When boiler capacity increases, the gas deflector, shown as pivotally mounted at 26, may be moved toward its dotted line position indicated in Fig. 3. Such action provides another path for the gases leaving the first section and one of less resistance than that across the second section. This reduces the flow of the gases passing over the secondary section ofthe superheater and tends to counteract the tendency of the superheater to produce higher superheats at increased boiler ratings when all of the gases sweep its surface. It will be seen that, as the deflector 24 is moved toward its dotted line position, more and more of the furnace gases may pass directly to the outlet 25 without sweeping over the secondary section of the superheater.

The deflector 24 is controlled from a position outside of the boiler setting, by a mechanism including a link 28 connected to an arm 30 which is non-rotatably mounted upon the shaft 32. The shaft 32 is rotatably supported in bearings which are preferably formed upon the casing 34. Within the casing there is shown a worm wheel 36 fixed upon the shaft 32 and arranged to be driven by a worm 38 journaled in the casing and having a handwheel 40 fixed thereto at its end.

The shaft 32 may, as indicated in Fig. 2, be connected to extension shafts 42 and M so that a number of the deflectors may be operated in unison. Fig. 2 shows an illustrative construction in which there are two control mechanisms, each extending halfway across the boiler installation. Fixed to arms iii are counter-balancing weights 48 which facilitate the operation of the control mechanism.

As indicated in the drawings, the links 28 are located between the horizontal circulators 50 and 52, and they pass through openings 5d and 56 provided in the gas confining walls of the boiler.

. These openings are wide enough to provide for the swinging of the links 28 from their full line positions to their dotted line positions as indicated in Fig. 3 of the drawings, and to maintain the opening 56 substantially closed during the operation of the control mechanism, cover plates 58 are provided. These plates slide in guidewa-ys provided by guides 68 and ,62, and are formed with openings M through which the links 28 are passed. Indicia 66 provided upon the casing 34 coact with the indicators 68 to show the positions of the superheat control mechanism.

When the deflectors 24 are in their full line positions indicated in Fig. 3, a maximum weight of furnace gases passes over the secondary section 22 of the superheater. In this position the deflectors cooperate with end baflles herein shown as plates Ill secured to the superheater tubes or loops. The major portion, and if desirable, all of the furnace gases pass between the wall H1 and the bafile 2d at low boiler ratings. The top of the wall 10 is preferably below the top of the bank of tubes Ii). Furthermore, it will be noted that the control mechanism including the deflectors 24 and the plates 10 are positioned in zones where the gas temperature is lower than elsewhere. This arrangement promotes the durability and long life of the control apparatus by preventing excessive overheating.

The particular steam boiler shown has downtake headers I2 connected at their lower ends to a mud drum 14 and at their upper ends to the water space of the drum I6 by downtake nipples 16 which are offset as indicated at 18 and 80 to afford a minimum resistance to the passage of gases to the outlet 25. The downtake headers are connected to uptake headers 82 by the steam generating tubes I8 and the former are connected at their upper ends to the steam space of the drum I6 by the horizontal circulators which have the upright portions 84. These portions may be said to be uptake nipples. The uptake headers are preferably pendently supported by hangers 86 fixed to the stationary frame structure 88.

As shown in Fig. l of the drawings some of the tubes of the uppermost row of steam generating tubes leading from the downtake headers 12 are connected at their upper ends to a header 90, which is a support for the superheater and which is preferably hung from an overhead beam by the hangers 92 and the auxiliary circulators 94. The latter may be connected to the drum 90 and be positioned between upright rows of the superheater tubes so as to afford an internal flow of boiler water for protecting the baffle 95 against overheating. At their discharge ends the circulators 94 are connected with the steam space of the drum.

Fig. 1 of the drawings shows a second superheater supporting header Illfl connected by tubes IE2 to the upper parts of the downtake headers I2. Between the header I00 and the row of downtake headers 12 a heat resisting inter-tube space filler or superimposed layer IE4 is supported by the tubes I02 to form a wall which, in this instance, causes all of the gases leaving the bank of water tubes It to pass to the superheater. This layer may consist of tile secured to the tubes I02.

Above the header IIJIJ, wall 20 is cooled by sup plementary circulators IE6 preferably located between upright rows of the superheater tubes and connected at their lower ends to the header Ill. Their upper ends I68 communicate directly with the steam space of the drum I6 and hangers ID are connected to the upper parts of these circu lators as shown.

Fig. 1 of the drawings also shows a superheater outlet header H2 supported by hangers H4 depending from the stationary structural member H5 and communicating with the superheater loops through outlet tubes I I8. These outlet tubes as well as the inlet tubes I20 are indicated as positioned in vertical rows with each row located between adjacent upright portions 84 of the circulators 50 and 52. On the gas side of the portion 84 of the circulator, the tubes of each of these upright rows are bent so that they form a single horizontal row of superheater tubes as indicated at I22. Thence the superheater loops continue in successively lower horizontal rows to the lowermost row I24 from which horizontal row the tubes are bent to form vertical rows of tubes I29 connected to the inlet headers I4.

The downtake headers of the boiler may be pendently supported by the nipples 16 from the drum I6 which is secured in a well known manner by strips secured to the structural frame work.

In order that the superheater tubes may be subject to a desirable gas distribution and gas contact, tile I31] are supported upon some of the tubes and preferably positioned between the upright rows which are spaced to accommodate the tubes 94 and IE6.

The drum I6 may be supplied with feed water in any suitable manner, and the outlet header I I2 of the superheater may be appropriately connected to apparatus which makes use of the superheated steam.

The furnace has walls I32 and I33, the latter of which includes wall cooling tubes I34 connected into fluid circulation by any suitable devices which may include the upper header I36.

Not only does this invention involve means for obtaining a close control of superheat over wide temperature ranges, but it also accomplishes this result with a minimum increase in draft when the gases are directed over a second section of the superheater. This is all done with a gas flow which is transverse to the tubes of the superheater. The superheater is provided with two sections with gas flowing transversely across the tubes in each section. A damper is provided which can be made to regulate the amount of gas flowing over the second section. With this arrangement, at high loads, the gas bypasses the second section giving a low draft loss through the superheater. At the low loads, where excess draft capacity is available, the gas is forced over the second section to increase the superheat.

What is claimed is:

1. In a drainable super-deck superheater for a single pass B. 86 W. boiler, a first baiile extending across the tubes of the superheater and separating first and second gas passes, a second bafile supported by the superheater tubes in the second gas pass and spaced from the first baffle, and a manually operable damper co-operating with the first and second bafiles to limit the opening of the second pass and to vary the total weight of the gases contacting with the superheater tubes in the second gas pass.

2. In apparatus of the class described, a steam boiler including a furnace and a bank of steam generating tubes, a single bank of superheater tubes, bafiies compelling the furnace gases to pass over the generating tubes and a part of the superheater in a single gas pass and then pass over another part of the superheater in a second gas pass, and means for varying only the proportion of the gases contacting the second part of the superheater in order to maintain constant superheat when boiler ratings vary, said superheater including tubes which extend through one of the baffles to form both superheater parts.

3. In a steam boiler, steam generating tubes, a bank of superheater tubes extending across the path of the furnace gases at a position beyond the steam generating tubes, a baflle wall extending across the superheater tubes and joined with a second baffie wall so extending from a side wall of the furnace as to shield a part of the bank from contact with the furnace gases until after they have contacted the remainder thereof, and

gas deflector means positioned beyond said remainder of the superheater and adjustable to control superheat by decreasing the proportion of the gases contacting with said part of the superheater as the boiler load increases.

CHARLES S. SMITH. 

